Mechanical system comprising a one-way clutch and alternator comprising such a system

ABSTRACT

The present invention relates to a mechanical system with a one-way clutch, for example a pulley for a motor vehicle alternator, comprising a first element and a second element which are able to move one with respect to the other in rotation about a central axis and delimit an annular housing radially to the central axis, a one-way clutch device arranged in the annular housing, and at least one rolling bearing arranged in the annular housing. The mechanical system is characterized in that the rolling bearing is an angular-contact bearing and comprises at least one pressed ring comprising means of attachment of the rolling bearing to the first element or the second element. The invention also relates to an alternator comprising such a mechanical system configured as a pulley with a one-way clutch.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a United States Non-Provisional Utility patentapplication claiming the benefit of French Patent Application Number1256821 filed on 13 Jul. 2012, which is incorporated herein in itsentirety. Applicants respectfully note, 13 Jul. 2013 falls on aSaturday; therefore, Applicants are afforded through the next businessday to maintain copendency.

TECHNICAL FIELD

The present invention relates to a mechanical system with a one-wayclutch, for example a pulley for a motor vehicle alternator. Theinvention also relates to an alternator comprising such a mechanicalsystem, configured as a pulley with one-way clutch.

BACKGROUND ART

In the known way, a transmission belt drives an external rim of analternator pulley, driving an internal hub. This pulley is subjected tonumerous variations in speed and torque while it is in service, notablybecause of the non-cyclic nature of the engine. There are various waysof smoothing these variations in speed and torque applied to the pulley,for example by fitting what is known as a one-way clutch (OWC) device,also known as a free wheel, between the hub and the rim. In onedirection of rotation, the one-way clutch device transmits the torquefrom the hub to the rim of the pulley, whereas in the other direction ofrotation the pulley operates as a free wheel.

WO-A-2011 079 963 and FR-A-2 726 059 each describe a mechanical systemof the pulley type for a motor vehicle alternator, comprising tworolling bearings and a one-way clutch device all arranged between a huband a rim.

In WO-A-2011 079 963, the rolling bearings are radial-contact ballbearings and their rings are machined. The clutch device comprises cams,and clutch trackways formed directly on the hub and the rim.

In FR-A-2 726 059, the rolling bearings are radial-contact roller orball bearings. The device comprises clutch trackways which can be formeddirectly on the hub and the rim. As an alternative, the clutch trackwaysmay be formed on pressed rings which are common to the clutch device andto the rolling bearings. In that case, the multifunctionality of therings is reduced because these rings cannot be adapted in terms ofmaterial, finish, functionality and performance specifically to theclutch device or to the rolling bearings. Moreover, one of the rings hasa radial discontinuity forming a means of attachment to the hub.Although the ring becomes easier to position, the axial clearancesinternal to the system are difficult to control.

DISCLOSURE OF INVENTION

It is an object of the present invention to propose an improvedmechanical system.

To this end, one subject of the invention is a mechanical system withone-way clutch, for example a pulley for a motor vehicle alternator,comprising a first element and a second element which are able to moveone with respect to the other in rotation about a central axis anddelimit an annular housing radially to the central axis, a one-wayclutch device arranged in the annular housing, and at least one rollingbearing arranged in the annular housing. The mechanical system ischaracterized in that the rolling bearing is an angular-contact bearingand comprises at least one pressed ring, comprising means of attachmentof the rolling bearing to the first element or the second element.

Thus, because of the angular contact and because of the means ofattachment, the invention improves the control over the axial clearancesand the axial load within the rolling bearing or bearings with which themechanical system is equipped. For preference, at least one pressed ringis separate from the member or members forming the clutch trackways ofthe one-way clutch device, which can have a special finish applied tothem, for example they can be machined or surface coated. In this case,the invention makes it possible to improve the operation and durabilityof the mechanical system because each of its constituent elements can beadapted specifically to suit its function. In addition, the pressedrings have a low cost of manufacture by comparison with machined rings.

According to other advantageous features of the invention, considered inisolation or in combination:

The means of attachment of the pressed ring include a discontinuity thatis radial overall, designed to collaborate with the first element or thesecond element in an axial direction parallel to the central axis.

The rolling bearing comprises at least one pressed ring distinct from amember or members forming a clutch trackway of the one-way clutchdevice.

The mechanical system also comprises at least one second rolling bearingincluding at least one pressed ring distinct from the member or membersforming the clutch trackway.

The rolling bearing or at least one of the rolling bearings with whichthe mechanical system is equipped includes two pressed rings distinctfrom the member or members forming the clutch trackway.

The one-way clutch device comprises at least one member that forms aclutch trackway and is distinct from the first element and the secondelement.

The first element and/or the second element forms a clutch trackway ofthe one-way clutch device.

The mechanical system comprises two angular-contact rolling bearingswhich are arranged one on each side of the one-way clutch device alongthe central axis, notably in an O or X setup, and which each comprise apressed ring pressed ring comprising means of attachment of the rollingbearing to the first element or the second element.

The mechanical system also comprises a pressing member for pressingagainst the pressed ring, which is designed to control the internalclearance of the rolling bearing provided with this pressed ring.

Another subject of the invention is an alternator comprising such amechanical system configured as a pulley with a one-way clutch.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be better understood on reading the description whichwill follow, given solely by way of nonlimiting example and made withreference to the attached drawings in which:

FIG. 1 is a view in axial section of a mechanical system according tothe invention, of the alternator pulley type, comprising rollingbearings and a one-way clutch device all arranged between a rim and ahub;

FIG. 2 is a view on a larger scale of detail II of FIG. 1; and

FIG. 3 is a view similar to FIG. 2 of a pulley according to a secondembodiment of the invention.

DETAILED DESCRIPTION

FIGS. 1 and 2 depict a pulley 1 according to the invention. This pulley1 is designed to be fitted to a motor vehicle alternator, which for thepurposes of simplification has not been depicted.

The pulley 1 is centred on a central axis X1 and comprises an externalrim 10, an internal hub 20, a one-way clutch device 30, a member 50, tworolling bearings 60 and 70 and two lateral shrouds 80 and 90. The rim 10and the hub 20 delimit a housing E1, of annular profile, about the axisX1. The elements 30, 50, 60, 70, 80 and 90 are arranged in this housingE1.

The rim 10 and the hub 20 are able to move one relative to the other inrotation about the central axis X1. The rim 10 comprises externalgrooves 12 configured partially to receive a transmission belt, whilethe hub 20 comprises an internal bore 21 configured to receive analternator shaft, the belt and the shaft not having been depicted forthe sake of simplicity. The rim 10 also comprises an internalcylindrical bore 11, while the hub 20 comprises an external land 22,together delimiting the housing E1. The land 22 comprises a centralcylindrical surface 24 and two lateral cylindrical surfaces 26 and 27having diameters slightly smaller than that of the surface 24, which runparallel to the axis X1. The surfaces 26 and 27 are connected to thissurface 24 by shoulders 28 and 29 respectively, which run radially tothe axis X1.

The device 30 arranged in the housing E1 allows the rim 10 to be engagedwith respect to the hub 20 which is capable of rotating in a firstdirection of rotation R1 about the central axis X1 and, conversely,allows the rim 10 to be disengaged from the hub 20 in a second directionof rotation R2 which is the opposite of the first direction of rotationR1. In the example of FIGS. 1 and 2, the device 30 comprises a cage 31surrounding the axis X1, and cams 32 which are held by the cage 31. Thecams 32 are distributed about the axis X1 and articulated such that theycan rotate with respect to the cage 31, each about an axis parallel tothe axis X1. Just one cam 32 positioned above the axis X1 has beendepicted in FIG. 1 for the sake of simplicity. The clutch is engagedthrough interaction between the cams 32 and clutch trackways, whichrotate as one with the first element 10 or with the second element 20.In the context of the invention, the clutch trackways form part ofelements that form integral parts of the clutch device 30.

Another example of a one-way clutch device 30 is described in documentWO-A-2011 079 963.

As shown in FIGS. 1 and 2, the member 50 is configured like an annularring centred on the axis X1. This member 50 is arranged between therolling bearings 60 and 70 in the housing E1, or in other words, isdistinct from the rolling bearings 60 and 70. The member 50 comprises aninternal cylindrical bore 51, and external cylindrical surfaces 52, 53and 54 which are centred on the axis X1. On the same side as the rollingbearing 60, the member 50 comprises an edge 56 which is configured as aradial annular surface and connects the surfaces 51 and 53. On the sameside as the rolling bearing 70, the member 50 comprises a part 57 whichruns radially away from the axis X1 from the surfaces 51 and 54. Themember 50 may be pressed, notably produced by pressing sheet metal. Thesurfaces 52, 53 and/or 54, which have different diameters, may bemachined.

The rolling bearings 60 and 70 are positioned beside the device 30 inthe housing El, on each side of this device 30 along the central axisX1. The rolling bearing 60 has an outer ring 61 and an inner ring 62between which rolling elements 63 of the ball type, held by a cage 64,are interposed. The rolling bearing 70 comprises a outer ring 71 and aninner ring 72 between which rolling elements 73 of the ball type held bya cage 74 are interposed. The rolling bearings 60 and 70 areangular-contact rolling bearings mounted in an X configuration in theexample of FIGS. 1 and 2. As an alternative, the rolling bearings 60 and70 may be arranged in an O setup. In the context of the invention, therings 61, 62, 71 and 72 are pressed, notably produced by pressing sheetmetal.

Furthermore, the internal rings 62 and 72 each comprise a radialdiscontinuity, 65 and 75 respectively, forming a means of attachment ofthe rolling bearing 60 or 70 to the hub 20. The discontinuity 65 pressesagainst the shoulder 28, while the discontinuity 75 presses against theshoulder 29. Collaboration between the discontinuities 65 and 75 and theshoulders 28 and 29 allows the rolling bearings 60 and 70 to bepositioned accurately along the axis X1. Also, this interaction holdsthe rolling bearings 60 and 70 axially in position, as detailedhereinafter in connection with the shrouds 80 and 90. In other words,each radial discontinuity 65 or 75 forms an axial end stop built intothe ring 62 or 72. Thus, the discontinuities 65 and 75 allow controlover the axial clearance between the rolling bearings 60 and 70 andaxial load applied to these rolling bearings 60 and 70.

In practice, the surfaces 11 and 52 form the clutch trackways of thedevice 30, these respectively facing towards and away from the axis X1.The surface 52 is smooth and preferably has a wear-resistant coating orsome other surface treatment suited to the present application. As analternative, the surface 52 may be grooved or toothed in order toincrease friction and increase the wedging of the cams 32 against theclutch trackway. Likewise, the surface 11 may have a wear-resistantcoating in the region intended to be in contact with the cams 32.

Advantageously, the pressed rings 61, 62, 71 and 72 of the rollingbearings 60 and 70 are distinct from the members 10 and 50 that form theclutch trackways 11 and 52. The trackway 11 is formed directly on therim 10 whereas the trackway 52 is formed by the member 50 distinct fromthe hub 20. Each element 10, 50, 61, 62, 71 and 72 may thus have ashape, a material and an arrangement all suited to its function,something which is not the case in existing systems in which the bearingrings and bearing raceways are formed as one and the same single piece.

For preference, the member 50 is in contact with just one ring of abearing 60 or 70. In this particular instance, the edge 56 is not incontact with the ring 62 of the rolling bearing 60, whereas the part 57is in contact with the ring 72 of the rolling bearing 70. As analternative, the member 50 is not in contact with either ring 62 or 72.Thus, the member 50 does not hamper the setting of the axial clearanceof the rolling bearings 60 and 70, as detailed hereinafter.

The lateral shrouds 80 and 90 associated with the rolling bearings 60and 70 respectively provide control over the axial clearance withinthese rolling bearings 60 and 70 and within the system 1. To do that,the shroud 80 comprises a pressing surface 81 for pressing against therolling bearing 60, whereas the shroud 90 comprises a pressing surface91 for pressing against the rolling bearing 70. The discontinuities 65and 75 form means of retaining the rolling bearings 60 and 70 in theaxial direction when the shrouds 80 and 90 are pressing against theserolling bearings 60 and 70.

The shroud 80 is arranged against the rolling bearing 60, on the outsideof the housing E1, on the other side of the rolling bearing 60 from thedevice 30. The shroud 80 comprises a U-shaped external part 82 on whichthe surface 81 is formed, and an internal part 83 which connects to thepart 82 and extends radially to the axis X1. The part 82 is fittedagainst the surface 11 of the rim 10. The part 83 supports a seal 89which is arranged in sealed contact with the surface 26 of the hub 20.The position of the shroud 80 along the axis X1 can be adjusted, suchthat the load applied by the surface 81 to the outer ring 61 can beadjusted, making it possible to control the axial clearance internal tothe rolling bearing 60. At the same time, the discontinuity 65 forms ameans of retention of the inner ring 62 in the axial direction parallelto the axis Xl.

By way of example, the position of the shroud 80 can be adjusted byscrewing into the rim 10 and, more specifically, by screwing the part 82with respect to the surface 11, although for the sake of simplicity, thecomplementary screw threads and tappings have not been depicted in thefigures. In another example, the shroud 80 may be push fitted into therim 10 and moved by axial pressure. Once in situ, the shroud 80 can befixed to the rim 10 and/or to the ring 61 by clamping, crimping, bondingor welding. As an alternative, the shroud 80 may be adjusted and/orfixed in position by any means suited to the present application.

Likewise, the shroud 90 is arranged against the rolling bearing 70, onthe outside of the housing E1, and on the other side of the rollingbearing 70 from the device 30. The shroud 90 comprises a U-shapedexternal part 92 on which the surface 91 is formed, and an internal part93 which connects to the part 92 and extends radially to the axis X1.The part 93 supports a seal 99 which is arranged in sealed contact withthe surface 27 of the hub 20. The position of the shroud 90 along theaxis X1 is adjustable, so that the load applied by the surface 91 to theouter ring 71 is adjustable, making it possible to control the axialclearance internal to the rolling bearing 70. At the same time, thediscontinuity 75 forms a means of retention of the inner ring 72 in theaxial direction parallel to the axis X1. The means for adjusting andfixing the position of the shroud 90 are comparable to those of theshroud 80.

Because the rolling bearings 60 and 70 are angular-contact bearings, theradial clearance is connected with the axial clearance internal to eachof these rolling bearings 60 and 70. The pressed rings 61 and 71 arecurved, with their concave side forming the raceway for the balls 63 and73 respectively. The pressing surfaces 81 and 91 are inclined withrespect to the radial parts 83 and 93 and to the convex external surfaceof the rings 61 and 71, facing the balls 63 and 73. Thus, the shrouds 80and 90 also make it possible to control the radial clearance internal toeach rolling bearing 60 and 70 as well as the axial clearance.

Furthermore, adjusting the clearances internal to the rolling bearings60 and 70 makes it possible to adjust the axial clearance within thesystem 1, between the rings 61, 62, 71 and 72 of the rolling bearings 60and 70, the device 30 and the member 50. Conversely, in existing systemscomprising a ring that is common to the clutch device and to the rollingbearings, such adjustment of the axial clearance is not possible.

The invention is not restricted to an alternator pulley comprising a huband a rim. Indeed the invention may be applied to any type of mechanicalsystem 1 comprising a first element 10 and a second element 20 which areable to move one relative to the other in rotation about a central axisX1, and between which a one-way clutch device 30 and at least onerolling bearing 60 are fitted. Clutch engagement is achieved bycollaboration between the device 30 and at least one clutch trackwayformed by a member that rotates as one with the first element 10 or withthe second element 20.

As an alternative that has not been depicted, the cage 31 supporting thecams 32 may be secured to one of the elements 10 or 20. In that case,the cams 32 with which the device 30 is equipped collaborate with justone single clutch trackway.

According to another alternative form of embodiment that has not beendepicted, the one-way clutch device 30 may be configured differentlyfrom a device involving cams.

According to another alternative form of embodiment that has not beendepicted, the pressing members 80 and 90 that press against a pressedring 61, 62, 71 or 72 may have any shape and/or arrangement suited tothe present application. For example, in the case of an O-type setup,the pressing surface 81 may be positioned against the inner ring 62.

According to another alternative form of embodiment that has not beendepicted, the system 1 has no member 50, which means that the clutchtrackways are formed directly on the rim 10 and the hub 20.

In another alternative form of embodiment that has not been depicted,the radial discontinuity 65 or 75 may be constrained in a groove, arecess or on a level step formed on the land 22.

According to another alternative form of embodiment which has not beendepicted, part of the radial discontinuity may be provided on an outerring 61 and/or 71, when the rolling bearings 60 and 70 are positioned inan O-type setup.

According to another alternative form of embodiment that has not beendepicted, the discontinuity 65 or 75 may be slightly inclined, forexample at an angle of between 0° and 45°, with respect to the directionradial to the central axis X1. In other words, in this case, thediscontinuity 65 or 75 is not strictly radial but may be qualified as adiscontinuity that is radial overall, designed to collaborate with therim 10 or the hub 20 in an axial direction parallel to the central axisX1.

According to another alternative form of embodiment that has not beendepicted, at least one of the rolling bearings 60 or 70 may comprise atleast one pressed ring 61, 62, 71 and/or 72 forming a bearing racewayfor the device 30. According to a particular example, each of the twopressed rings of one of the rolling bearings 60 or 70 may form a bearingraceway for the device 30.

FIG. 3 depicts a second embodiment of a pulley 101.

Certain constituent elements of the pulley 101 are identical to theconstituent elements of the pulley 1 of the first embodiment, describedabove, and bear the same references. These are the elements 10, 20, 50,60, 70, 89 and 99.

Other constituent elements of the pulley 101 are comparable to theconstituent elements of the pulley 101, and bear the same referencesincreased by 100. These are the device 130 comprising a cage 131 andcams 132, and shrouds 180 and 190 comprising pressing surfaces 181 and191 and parts 182, 183, 192 and 193.

The pulley 101 further comprises a member 140 comparable to the member50. The member 140 is arranged in the housing El between the rollingbearings 60 and 70, facing the member 50. The member 140 is configuredlike an annular ring centred on the axis X1 and is distinct from therings 62 and 72 of the rolling bearings 60 and 70. The member 140comprises an internal cylindrical bore 141 and an external cylindricalsurface 152, which are centred on the axis X1. On the same side as therolling bearing 60, the member 140 comprises a part 146 which extendsradially away from the axis X1. On the same side as the rolling bearing70, the member 140 comprises an edge 147 which is configured like aradial annular surface. The member 140 can be produced by pressing.

In practice, the surfaces 52 and 141 form the clutch trackways of thedevice 130 facing respectively away from and towards the axis X1. Thesurfaces 52 and 141 are smooth and preferably have a wear-resistantcoating. As an alternative, the surfaces 52 and 141 may be grooved ortoothed to increase friction and the jamming of the cams 132 on theclutch trackway. Advantageously, the pressed rings 61, 62, 71 and 72 ofthe rolling bearings 60 and 70 are distinct from the members 50 and 140that form the clutch trackways 52 and 141.

The shrouds 180 and 190 have a slightly different structure, but asimilar operation, by comparison with the shrouds 80 and 90 of the firstembodiment. The shrouds 180 and 190 are depicted away from the rollingbearings 60 and 70, before their position has been adjusted and fixed.The external part 182 extends axially from the radial internal part 183as far as the pressing surface 181. The external part 192 extendsaxially from the radial internal part 193 to the pressing surface 191.More specifically, an edge corner of the surfaces 181 and 191 will pressagainst the rings 61 and 71 because of their curved profile.Furthermore, the shrouds 180 and 190 can be adjusted and fixed inposition by means comparable to those used for the shrouds 80 and 90.

Whatever the embodiment, the mechanical system 1 or 101 comprises atleast one angular-contact rolling bearing 60 and/or 70 comprising atleast one pressed ring 61, 62, 71 and/or 72 comprising means 65 and/or75 of attachment of the rolling bearing 60 or 70 to the first element 10or the second element 20. Preferably, at least one pressed ring 61, 62,71 and/or 72 is distinct from the member or members 10, 50 and/or 140forming one of the clutch trackways 11, 52 or 141 of the one-way clutchdevice 30 or 130.

Furthermore, all or some of the technical features of the variousembodiments can be combined with one another. Thus, the mechanicalsystem may be adapted in terms of cost, functionality and performance.

What is claimed is:
 1. A mechanical system with a one-way clutch, forexample a pulley for a motor vehicle alternator, comprising: a firstelement and a second element which are able to move one with respect tothe other in rotation about a central axis and delimit an annularhousing radially to the central axis, a one-way clutch device arrangedin the annular housing, and at least one rolling bearing arranged in theannular housing, wherein the rolling bearing is an angular-contactbearing and comprises at least one pressed ring comprising an attachmentfeature for attaching the rolling bearing to one of the first element orthe second element.
 2. The mechanical system according to claim 1,wherein the attachment feature of the pressed ring includes adiscontinuity that is radial overall, designed to collaborate with oneof the first element or the second element in an axial directionparallel to the central axis.
 3. The mechanical system according toclaim 1, the rolling bearing further comprising at least one pressedring distinct from at least one member forming a clutch trackway of theone-way clutch device.
 4. The mechanical system according to claim 3,further comprising at least one second rolling bearing including atleast one pressed ring, wherein the at least one pressed ring isdistinct from the at least one member forming the clutch trackway. 5.The mechanical system according to claim 3, wherein at least one of therolling bearings with which the mechanical system is equipped furthercomprises two pressed rings distinct from the at least one memberforming the clutch trackway.
 6. The mechanical system according to claim1, wherein the one-way clutch device further comprises at least onemember that forms a clutch trackway and the one-way clutch device isdistinct from the first element and the second element.
 7. Themechanical system according to claim 1, wherein at least one of thefirst element and the second element forms a clutch trackway of theone-way clutch device.
 8. The mechanical system according to claim 1,further comprising two angular-contact rolling bearings which arearranged having one angular-contact rolling bearing located on each sideof the one-way clutch device along the central axis, notably in one ofan 0 or X setup, and which each angular-contact rolling bearing comprisea pressed ring comprising an attachment feature for coupling the rollingbearing to one of the first element or the second element.
 9. Themechanical system according to claim 1, further comprising a pressingmember for pressing against the pressing ring, wherein the pressingmember is designed to control the clearance internal to the rollingbearing equipped with this pressed ring.
 10. An alternator incorporatinga one-way clutch, comprising: an electromechanical device comprising arotational member for converting rotational mechanical energy toelectrical energy a pulley affixed to the rotational member; a clutchintegrated between the pulley and the rotational member, the clutchcomprising: a first element and a second element which are able to moveone with respect to the other in rotation about a central axis anddelimit an annular housing radially to the central axis, a one-wayclutch device arranged in the annular housing, and at least one rollingbearing arranged in the annular housing, wherein the rolling bearing isan angular-contact bearing and comprises at least one pressed ringcomprising an attachment feature for attaching the rolling bearing toone of the first element or the second element.
 11. The alternatoraccording to claim 10, wherein the attachment feature of the pressedring includes a discontinuity that is radial overall, designed tocollaborate with one of the first element or the second element in anaxial direction parallel to the central axis.
 12. The alternatoraccording to claim 10, the rolling bearing further comprising at leastone pressed ring distinct from at least one member forming a clutchtrackway of the one-way clutch device.
 13. The alternator according toclaim 12, the clutch further comprising at least one second rollingbearing including at least one pressed ring, wherein the at least onepressed ring is distinct from the at least one member forming the clutchtrackway.
 14. The alternator according to claim 12, wherein at least oneof the rolling bearings with which the mechanical system is equippedfurther comprises two pressed rings distinct from the at least onemember forming the clutch trackway.
 15. The alternator according toclaim 10, wherein the one-way clutch device further comprises at leastone member that forms a clutch trackway and the one-way clutch device isdistinct from the first element and the second element.
 16. Thealternator according to claim 10, wherein at least one of the firstelement and the second element forms a clutch trackway of the one-wayclutch device.
 17. The alternator according to claim 10, the clutchfurther comprising two angular-contact rolling bearings which arearranged having one angular-contact rolling bearing located on each sideof the one-way clutch device along the central axis, notably in one ofan O or X setup, and which each angular-contact rolling bearing comprisea pressed ring comprising an attachment feature for coupling the rollingbearing to one of the first element or the second element.
 18. Thealternator according to claim 10, the clutch further comprising apressing member for pressing against the pressing ring, wherein thepressing member is designed to control the clearance internal to therolling bearing equipped with this pressed ring.